Justification:
The species was known from the Los Angeles River drainage, in streams near San Gabriel and Pasadena (Los Angeles County) and Warm Creek (San Bernardino County), California (USA). The species is only known from approximately 100 specimens, collected between 1897 and 1933 (Martin and Wicksten 2004). The most recently collected specimens were in 1933. Extensive surveys for the species have taken place since 1968 and continue sporadically to the present day, surveys have extended from the Mexican border north to Santa Barbara (Martin and Wicksten 2004), but no further specimens of the species have been found. The habitat of the species throughout its known historical range has been destroyed by channelization and urbanization and now forms part of the Greater Los Angeles area. The species is thus considered to be Extinct.

The species was known from the Los Angeles River drainage, in streams near San Gabriel and Pasadena (Los Angeles County) and Warm Creek (San Bernardino County), California (USA) (Martin and Wicksten 2004).